Semiconductor device

Abstract

A semiconductor device in an embodiment includes a plurality of first trenches which are recessed on one side in a thickness direction of a semiconductor substrate and have a first electrode accommodated therein. The semiconductor device includes a second trench which is recessed on the one side in the thickness direction and has a second electrode accommodated therein. When viewed from the thickness direction, the second trench surrounds each of the plurality of first trenches. The second trench includes a plurality of first extension portions which extend in a first direction which is orthogonal to the thickness direction and a plurality of second extension portions which extend in a second direction which is orthogonal to the thickness direction and intersects the first direction. A width of each of the plurality of second extension portions is narrower than a width of each of the plurality of first extension portions.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a plurality of first trenches which are recessed from a surface of a semiconductor substrate toward one side in a thickness direction of the semiconductor substrate and has a first electrode accommodated therein;   a second trench which is recessed from the surface toward the one side in the thickness direction and has a second electrode accommodated therein;   a first conductivity type base layer which is disposed between the first trench and the second trench and surrounds the first electrode;   a second conductivity type source layer which is disposed on the other side of the base layer in the thickness direction, in contact with the base layer, and surrounds the first electrode;   a second conductivity type drift layer which is disposed on the one side of the base layer in the thickness direction and in contact with the base layer; and   a source electrode which is disposed on the other side of the semiconductor substrate in the thickness direction and electrically connected to the first electrodes and the source layer;   wherein, when viewed from the thickness direction, the second trench surrounds each of the first trenches,   the second trench has a plurality of first extension portions which extend in a first direction orthogonal to the thickness direction and a plurality of second extension portions which extend in a second direction which is orthogonal to the thickness direction and intersects the first direction, and   a width of each of the second extension portions is narrower than a width of each of the first extension portions.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein a conductive portion which is connected to the second electrode is disposed in each of the first extension portions. 
     
     
         3 . The semiconductor device according to  claim 2 , wherein a second conductive portion which is connected to the second electrode is disposed in each of the second extension portions, and
 the second conductive portion is connected to the conductive portion.   
     
     
         4 . The semiconductor device according to  claim 2 , wherein a resistivity of the conductive portion is smaller than a resistivity of the second electrode. 
     
     
         5 . The semiconductor device according to  claim 2 , wherein the conductive portion is made of tungsten. 
     
     
         6 . The semiconductor device according to  claim 1 , wherein a gap in a first direction between imaginary lines adjacent to each other in the first direction among imaginary lines extending in the second direction and passing through centers of the plurality of first trenches is smaller than a gap between the first trenches in the second direction. 
     
     
         7 . The semiconductor device according to  claim 1 , wherein, when viewed from the thickness direction, lengths of three sides of a triangle having centers of the three first trenches disposed adjacent to each other as vertexes are the same. 
     
     
         8 . The semiconductor device according to  claim 1 , wherein a gap between the first trenches in the first direction and a gap between the first trenches in the second direction have the same dimension. 
     
     
         9 . The semiconductor device according to  claim 1 , wherein, when viewed from the thickness direction, a rectangle having centers of the four first trenches disposed adjacent to each other as vertexes is a square. 
     
     
         10 . The semiconductor device according to  claim 1 , wherein each of the first extension portions is disposed between the first trenches which are adjacent to each other in the second direction, and
 each of the second extension portions is disposed between the first trenches disposed adjacent to each other in the first direction and extends in the second direction orthogonal to the first direction.   
     
     
         11 . The semiconductor device according to  claim 1 , wherein the second trench includes third extension portions which extend in a third direction which is orthogonal to the thickness direction and intersects both the first direction and the second direction,
 each of the first extension portions is disposed between the first trenches which are adjacent to each other in a direction which is orthogonal to both the thickness direction and the first direction,   the plurality of second extension portions are disposed between the first trenches which are adjacent to each other in a direction which is orthogonal to the second direction,   the plurality of third extension portions are disposed between the first trenches which are adjacent to each other in a direction which is orthogonal to the third direction, and   when viewed from the thickness direction, the second trench has a honeycomb shape in which it surrounds each of the first trenches.